球形表面富锰Mn_(x)Co_(3-x)O_(4-η)尖晶石型催化剂选择性催化还原NO_(x)研究  

Spherical Mn_(x)Co_(3−x)O_(4−ƞ)Spinel with Mn-Enriched Surface as High-Efficiency Catalysts for Low-Temperature Selective Catalytic Reduction of NO_(x)by NH_(3)

作　　者：高凤雨 刘恒恒 姚小龙 Zaharaddeen Sani 唐晓龙 罗宁 易红宏 赵顺征 于庆君 周远松 Fengyu Gao;Hengheng Liu;Xiaolong Yao;Zaharaddeen Sani;Xiaolong Tang;Ning Luo;Honghong Yi;Shunzheng Zhao;Qingjun Yu;Yuansong Zhou(Beijing Key Laboratory of Resource-oriented Treatment of Industrial Pollutants,School of Energy and Environmental Engineering,University of Science and Technology Beijing,Beijing 100083,China;Key Laboratory of Cleaner Production and Integrated Resource Utilization of China National Light Industry,Beijing Technology and Business University,Beijing 100048,China;Department of Science Laboratory Technology,Federal Polytechnic Daura,P.M.B.1049 Daura,Kastina State,Nigeria)

机构地区：[1]北京科技大学能源与环境工程学院,工业典型污染物资源化处理北京市重点实验室,北京100083 [2]中国轻工业清洁生产和资源综合利用重点实验室(北京工商大学),北京100048 [3]Department of Science Laboratory Technology,Federal Polytechnic Daura,P.M.B.1049 Daura,Kastina State,Nigeria

出　　处：《物理化学学报》2023年第9期136-148,共13页Acta Physico-Chimica Sinica

基　　金：中国轻工业清洁生产和资源综合利用重点实验室开放课题基金(CP2021YB02);国家自然科学基金(U20A20130,21806009);中央高校基本科研业务费(06500152)资助。

摘　　要：采用共沉淀法制备了高比表面积的Mn_(x)Co_(3-x)O_(4)球形催化剂,研究了NH3选择性催化还原NOx性能。Mn-Co金属氧化物具有尖晶石结构,随着Co含量的增加,晶体结构由四方相转变为立方相。高浓度的表面活性氧物种和变价元素的强有效电子转移(Co^(3+)+Mn^(3+)↔Co^(2+)+Mn^(4+))有利于提高Mn_(x)Co_(3-x)O_(4)(x=1.0、1.5、2.0)尖晶型石催化剂的氧化还原能力,催化剂表面的Mn富集作用形成了氧缺陷结构和丰富的表面活性位点,进一步促进SCR脱硝反应,呈现出优异的催化性能。COtet(CoMn)octO_(4)晶体结构中,Mn离子(Mn^(3+)和Mn^(4+),以三价锰为主)和部分Co离子被配置到八面体中心,这些物种作为活性位点存在着较强的电子转移交互作用,该构型对促进低温脱硝活性和保护活性位点耐受SO_(2)毒害具有重要的意义。Mn-Co尖晶石表面的NH_(3)-SCR脱硝反应过程主要遵循Eley-Rideal反应机理,即吸附态NH_(3)与气态NO(或NO_(2))的反应路径。随着反应温度的增加,反应生成的NH_(4)NO_(3)中间体很可能转化为NH_(4)NO_(2)物种,进而分解为N_(2),提高了催化剂的氮气选择性。Currently,there is an urgent need to develop an efficient,nontoxic,and stable catalyst for the removal of NO_(x)via selective catalytic reduction using NH_(3)(NH_(3)-SCR)that is effective at low temperatures.Mnbased catalysts are particularly representative and have been widely studied.An investigation of the collaborative participation of Mn and Co can be of great importance for improving the catalytic activity and SO_(2)resistance of Mn-Co oxides with a spinel structure.Therefore,in this study,we prepared Mn_(x)Co_(3-x)O_(4)spherical particles with high surface area using a coprecipitation method and investigated their ability to remove NO_(x)via NH_(3)-SCR.Mn-Co bimetal oxides mainly possess a spinel structure and undergo a tetragonal-to-cubic phase transformation with increasing Co-content.A high concentration of surface oxygen and strong effective electron transfer between the variable valence elements(Co^(3+)+Mn^(3+)↔Co^(2+)+Mn^(4+))improves the redox ability of typical Mn_(x)Co_(3-x)O_(4)(x=1.0,1.5,2.0)spinel catalysts.In addition,Mn-enrichment leads to more oxygen vacancies and abundant surface-active sites,which further promotes the SCR catalytic performance.The investigated Mn_(x)Co_(3-x)O_(4)catalysts exhibit>91%NO_(x)conversion at 75℃,almost reaching 100%conversion with increasing reaction temperature.Notably,the NO_(x)conversion rate remained above 80%during the test time of 15 h under 150×10^(−6)SO_(2)at 175°C.It was found that the coordination structure likely formed into a Cotet(CoMn)octO_(4)spinel structure in which Mn ions(Mn^(3+)and Mn^(4+),mainly in trivalent manganese)and partial Co ions are configured into octahedral sites.These species were identified as the activity descriptor for probably owing to their strong electronic transfer interactions that were directly correlated with SCR activity.Furthermore,the Cotet(CoMn)octO_(4)configuration was important for promoting low-temperature de-NO_(x)activity and highly conducive to protecting Mn active sites from poisoning by SO_(2).The act

关 键 词：Mn-Co复合氧化物 尖晶石结构 富锰表面 选择性催化还原 协同作用 反应机理 

分 类 号：O643[理学—物理化学]